US1771717A

US1771717A - Thermionic tube

Info

Publication number: US1771717A
Application number: US169431A
Authority: US
Inventors: Lubcke Ernst
Original assignee: Siemens AG
Current assignee: Siemens and Halske AG; Siemens AG
Priority date: 1926-02-26
Filing date: 1927-02-19
Publication date: 1930-07-29
Anticipated expiration: 1947-07-29

Description

July 29, 1930. E LUBCKE 1,771,717

THERMI ON I C TUBE Filed Feb. 19, 1927 INVENTOR Pmmahynmao UNITED STATES PATENT OFFICE mar 1mm, 01' BIBLINBS'IAM, Gm, LSSIGHOB TO 51MB 6: mm, AKI'IENGEBELLSOHAF'I, O! BIEKINSSTADT, mum BERLIN, am, A.

CORPORATION O1 Gm 'ramromc ma Application fled I'ebraary 19, 1887, lerlal Io. 189,431, and in Germany February 88, 1989.

This invention relates to a thermionic tube and more particularly to a tube using an arc as a source of electrons.

Discharge tubes for the amplification of p electrical currents and the production of electrical oscillations are known in whichthe incandescent filament is replaced by a spontaneous or unassisted arc discharge. In these devices, one disturbing element is that the current flowing across the arc is not constant, with the result that current surges or rushes (impulses) are super osed upon the are current, and these maye of such a value that the use of the are as an electron source for many purposes becomes questionable.

It is an object of this invention to avoid variations in the strength of the arc current. According to the present invention, a distinct electron source is provided. above the filament go of the are discharge. For this purpose, for instance, one or more heated electrodes may be disposed above the surface of the main cathode, or else one or more discharges (arcs) may be maintained. Another scheme would be to use the cathode itself as a base for the auxiliary arcs.

The accom anying drawing shows two embodiments o' the basic idea of the invention by way of example. 7

Figure 1 is a section through a tube utillzing a mercury are, having an auxiliary cathode of the filament type, and

Figure 2 is a section through a similar tube with another type of auxiliary cathode.

Referring 'to the embodiment shown in Figure 1, 1 is the main cathode, 2 the main anode, 3 the control grid, and 4 the amplifier anode. In order to insure as great as possible a constancy of the arc current flowing between cathode 1 and anode 2,a hot'filament 6 supplied from batte the cathode surface. f course, in lieu of onl one hot filament, a plurality thereof co d be provided, and these should then be uniforml distributed around the periphery of the tu 7 is a screen which is designed to prevent precipitation or condensation of droplets of'mercury upon the filament 6. To insure abundant electron emission from fila- M ment 6, the same in well known manner may 5 is disposed above p be coated with a film of oxide or thorium.

Under certain circumstances, it may also be suitable to use filaments coated with hydrides of alkaline earths. Figure 2 shows another embodiment of the lnvention. 8 is a discharge vessel, 9 the main cathode, 10 the main anode, 11 the control End, and 12 the amplifier anode. In the midle of cathode 9 is secured a pin 13 which is made of zirconium or hafnium oxideQ But 1t may also have the composition of and be made like the glowers used in Nernst lamps. The top part of said pin 13 may be electrically heate by heater spiral 14. If by the aid of the spiral 14 the end of the pin 13 is caused to incandesce, then an arc W111 be set up in the direct neighborhood of the pin, emission being automatically regulated by its own current. The end of pin 13 may be coated with oxldes of alkaline metals, h drides of alkaline earth metals, and the H e.

The operation of the device as here disclosed is probably predicated upon the fact that the electrons or ions issuing from the hot' filament or at the auxiliary discharge partly compensate the s ace-charge at the cathode, or upon the fact t at the same diminish the requisite ener expenditure normally covered or supplie by the arc discharge b causin the detachment of electrons from t e cath c.

Having thus described my invention, what I claim 19: t

1. In an electron discharge device, an anode an auxiliary anode, agrid, a primary cathode consistin of liquid mercury, and a secondary catho c, said secondary. cathode comprisin a pin of electron-emissive material exten g through and above the primary cathode, and a heating coil within said 2. In an electron discharge device, a primary anode, a secondary anode, a grid, a primary cathode compilrising liquid mercury, and a secondary cat ode comprising an oxide in of electron-emissive material extending through and above the li uid mercury, and a heating coil within t e pin to cause the said pin to incandesce.

- ERNST LUBGKE.